Snow tractor



Jan. 22, 1946.

'A. M. COCHRAN snow TRACTOR Filed April 16, 1943 L L L m f INVENTORAVERY u. cocnmw ATTORNEYS 4 Patented Jan. 22, 1946 up i'ca onjmjnjrs,rsiaflseriai ir -483.341 ;jl w ot-eats. (orriso al- (Granted under.the, act of..March .3, .1883, {as I V amended Aprllfilfl, i928 310:0.1G..75 7)f v The 1 invention i described herein may be2manuifacturedandusedby or *for the Governmentufor governmental :p'urpose's,withoutthe paymentft'o "me otany royaltythereon.

j Theprese'nt invention pertains to a novel -snow tractor .BIl'dmOIGIDaItiCIIIaIIY 130 one that can replace' fio'gs as the motive powerin haulin'g a lead .over a trail and similarly to replace snowshoers inbreakin a new trail in 'fresh'snow."

Ordinarily a trail in fresh snow is first broken by snowshoers.Frequently it must remain unused overnight in order to harden before itis serviceable. Such a trail is designed to be "traveled by dog-drawnsleds or toboggans. This mode of transportation is difficult even undernormal conditions. on the feet of the dogs, especially on an incline,

. their legs sink into the snow and thus retard Due to the concentratedload ,progress very materially. Moreover, special skill' andunderstanding are required in handling the dogs. For example, the drivermust know when they require rest for, if overworked, they become subjectto stroke. In addition,'food for the dogs must be carried, and the sizeof the pay load is reduced in proportion to the length of the trip.

The difiiculties are greatly enlarged where the terrain is at allirregular; one part of the sled may be on a softer surface than anotherpart, causing the sled to tilt and requiring steerin of the dogs, moreeffort by the dogs, or both. In fact, the density of the snow is morethan likely than not to be nonuniform, and th tilting of the sled ismore or less usual. Tilting also occurs on striking hard spots such asrocks and stumps.

The greatest difficulties are presented in break- Even on level ground,

ing a trail or hauling a load across a fairly steep slope. In the lattercase the loaded toboggans tend to slide down the slope and aremaintained on their course by the use of gee poles. The dogs. however,are not so easily controlled while slipition and-iarea, with-respect toits weight, t'hat its mutation in snow produces a fresh trail ofapproximately thefisame depth as a trail made'nby snowshoers: Such a=trailwill support the usual :lo'ad :c onsisting of laden 'tobogganspreceded and steered individually -by snowshoers holding the gee poles;:iin'other 'important property is a; Canitr of ravity iloca'ted rather';close' to the bottom" iniorder to reduce the tilting. This is "accom-'plished fby mounting:the power plant on the --tractor in a lowposition.Another desirable feature 'isithat the tractorgor'the trail makingpartthereof, has approximately the width of a snow-shoe trail, which isabout twenty inches.

Finally, the steering means for the tractor is of great importance. Apair of handle bars extending longitudinally from the rear are providedfor normal steering. 'In this connection a center of gravity located toofar'forward would increase the difficulty in steering; neither should itbe too far rearward for this .would increase'the swaying. Ithas beenfound that the most desirable location of the center of gravity isslightly forward of the longitudinal center.

In traversing diflicult terrain, as in crossing a slope, the handle barsat the rear are not sufficient to maintain the tractor on its course. Tofacilitate steering under such conditions, another manhandling means isprovided at the front of the tractor. This may conveniently be a geepole at the front. end, whereby the tractor can be man-handled at bothends. Inthis way the steering is completely within the control of one ortwo men, as the case may be, and is no longer dependent upon suchuncertainties as thetemperament, fatigue and cooperation of a team ofdogs. a

The invention is fully disclosed by way of,.example in the followingdescription and in the accompanying drawing in which;

Figure 1 is a front end View of the device,

, partly broken away, and

ping and tugging. The driver can keep them on p the course only bytalking to them. This becomes increasingly difficult as the dogs growtired, and only the most skillful driver can succeed in this operation.At best his control over the steerin is indirect, incomplete andnon-mechanical.

'In alleviating these difficulties, the invention provides a powerdriven tractor-to replace the dogs in hauling the load. It is alsouseful in breaking the trail. To accomplish these functionssatisfactorily, I have found that the tractor must have certain definiteproperties. The bottom of the tractor should be of such' construc-Figure 2 is a side elevation of the device.

a Reference to these views will now be made by us of like characterswhich are employed to designate correspondin parts throughout.

In Figure 1 the tractor is illustrated as built on a suitable, frameworkcomprising, in this case,

a' pair of rectangular frames I made of tubing and joined by transversebars or tubes 2. This structure in the illustrated embodiment rests on atoboggan bottom or skid plate 3.

Sprocket wheels 4 are suitably journaled at the eight corners of theframework, and over them are passed two chains 5. Grippers or flights 6w re are secured across the chains in spaced relation to form aso-called open track. However, the specific construction of the track isnot material and may be modified as already indicated.

-The power plant is in the form of a gasoline motor designated by thenumeral 1 and supplied with fuel from a tank I. It is operativelyconnected through gearing vor a transmission 8 to rear lower wheels 4;The motor is preferably mounted low and slightly forward of the center 7of the skid plate 3 to facilitate steering and to reduce tilting andswaying. The weight of the tractor is 300 to 400 pounds.

The flotation of the tractor is such that it makes a trail in fresh snowhaving approximately 7 tion has been illustrated and described, it willbe the same width and depth as one made by snowshoers in the usualmanner. The trail is thus adapted to carry the usual loads.

Handle bars l0 are extended rearwardly from the framework, preferablyits lower portion, and are provided at the upper ends with controllevers ll linked to the motors Rings l2 are attached near the lower endsof the bars H! for towing a toboggan or a train of them. Similarly, abracket l3 on the forward part of the framework carries a ring H for atowing bridle. Finally, a socket I5 is mounted on the framework,preferably at the upper forward corner of the right hand side, toreceive a gee pole I6, extending a sufficient distance upwardly beyondthe upper laps of the chains 5.

The. operation of the device will be briefly understood that variousalterations in the details of construction may be made without departingfrom the scope of the invention as indicated by the appended claim.

What I claim is:

A self-propelled tractor comprising a light,

comparatively high, rhomboidal shaped frame having the upper forward endthereof projecting outwardly, sprocket wheels disposed on each corner ofsaid frame, a comparatively wide light track substantially the width ofsaid frame engaging said sprockets and movable around said frame; powermeans within said frame for moving said track, and angularly extendinghandle bars projecting from the lower rear corner of said frame formanuallyhandling said tractor, said frame and track shielding said powermeans in said frame. AVERY M. COCHRAN.

